feat(api): pass current_depth to retain's' callback

Author: KSXGitHub

src/data_tree/retain.rs

@@ -7,16 +7,30 @@ where
     Self: Send,
     Size: size::Size,
 {
-    /// Recursively cull all descendants that do not satisfy given `predicate`, in parallel.
-    pub fn par_retain(&mut self, predicate: impl Fn(&Self) -> bool + Copy + Sync) {
-        self.children.retain(predicate);
+    /// Internal function to be used by [`Self::par_retain`].
+    fn par_retain_with_depth(
+        &mut self,
+        current_depth: u64,
+        predicate: impl Fn(&Self, u64) -> bool + Copy + Sync,
+    ) {
+        self.children
+            .retain(|child| predicate(child, current_depth));
+        let next_depth = current_depth + 1;
         self.children
             .par_iter_mut()
-            .for_each(|child| child.par_retain(predicate));
+            .for_each(|child| child.par_retain_with_depth(next_depth, predicate))
+    }
+
+    /// Recursively cull all descendants that do not satisfy given `predicate`, in parallel.
+    pub fn par_retain(&mut self, predicate: impl Fn(&Self, u64) -> bool + Copy + Sync) {
+        self.par_retain_with_depth(0, predicate)
     }
 
     /// Process the tree via [`par_retain`](Self::par_retain) method.
-    pub fn into_par_retained(mut self, predicate: impl Fn(&Self) -> bool + Copy + Sync) -> Self {
+    pub fn into_par_retained(
+        mut self,
+        predicate: impl Fn(&Self, u64) -> bool + Copy + Sync,
+    ) -> Self {
         self.par_retain(predicate);
         self
     }
@@ -28,7 +42,7 @@ where
         Size: Into<u64>,
     {
         let minimal = self.size().into() as f32 * min_ratio;
-        self.par_retain(|descendant| descendant.size().into() as f32 >= minimal);
+        self.par_retain(|descendant, _| descendant.size().into() as f32 >= minimal);
     }
 
     /// Process the tree via [`par_cull_insignificant_data`](Self::par_cull_insignificant_data) method.

src/data_tree/retain/test.rs

@@ -157,7 +157,7 @@ fn edge_cases() {
             ),
         ],
     )
-    .into_par_retained(|descendant| descendant.name().starts_with('!').not())
+    .into_par_retained(|descendant, _| descendant.name().starts_with('!').not())
     .into_reflection();
     let expected = dir(
         "root",